Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the brain, which is characterized by the memory deterioration, behavioral disturbances, impairment of activities of daily living, and loss of independent function. It is thought that 18-24 million people in the world are currently suffering from AD, two-thirds of whom are living in developed or developing countries. This number is expected to reach 34 million by 2025.
AD is a complicated disease. It may even be the result of more than one disease. It is characterized by an accumulation of insoluble aggregates of amyloid-beta peptide (Aβ). such as Aβ oligomers. These aggregates or oligomers are associated with cell inflammatory response and are thought to bind to a surface receptor on neurons and change the structure of the synapse, thereby disrupting neuronal communication. Due to the minute amount produced per day (22-27 ng/day) and accumulated for years (about 7-10 mg in brains of AD subjects), this daily inflammatory response is invisible and not associated with any major symptoms. In addition, tau protein abnormalities are thought to play a role in the disease cascade. Hyperphosphorylated tau proteins are thought to pair with other threads of tau. Eventually, they form neurofibrillary tangles inside nerve cell bodies. When this occurs, the microtubules disintegrate, collapsing the neuron's transport system. This may result first in malfunctions in biochemical communication between neurons and later in the death of the cells.
The recent failures of several promising drugs have spurred greater urgency to investigate new targets and their interconnectedness. That said, new therapies for Alzheimer's are needed.